FIG. 1 depicts a portion of a conventional read transducer 10, which may be part of a conventional merged head including the conventional read transducer 10 and a write transducer (not shown). The conventional read transducer 10 includes a conventional shield 12, a conventional insulator 14, read sensor 16, conventional seed layers 18A and 18B, conventional hard bias structures 20A and 20B, conventional leads 22A and 22B, conventional insulator 24, and conventional shield 26. Typically, the read sensor 16 is a magnetoresistive or giant magnetoresistive sensor, such as a spin valve or a tunneling magnetoresistive junction. In such a case, the read sensor 16 would typically include at least an antiferromagnetic pinning layer, a magnetic pinned layer adjacent to the antiferromagnetic pinning layer, a nonmagnetic spacer layer, and a free layer. For simplicity, these layers are not separately shown in FIG. 1. The magnetization of the free layer changes direction based upon the magnetic field from a recording medium (not shown). The change in the relative orientations of the magnetization of the free and pinned layers alters the resistance of the read sensor 16. Thus, the read sensor 16 allows the conventional magnetic transducer 10 to read data.
The conventional insulators 14 and 24 are used to electrically insulate the read sensor 16. The conventional shields 12 and 26 are used to magnetically isolate the read sensor 16. Thus, only the magnetic field from the portion of the recording media desired to be read is experienced by the conventional read sensor 16. The conventional leads 22A and 22B are used to carry current to and from the conventional read sensor 16. The current can be used to sense the resistance of the read sensor 16, and thus read the stored data in the recording media.
FIG. 2 depicts a close-up view of a portion of the conventional read transducer 10. In particular, the conventional hard bias structure 20A/20B, the conventional seed layer 18A/18B, and the insulator 14 are shown. Referring to FIGS. 1 and 2, the conventional seed layer 18A/18B is formed prior to the conventional hard bias structure 20A/20B. The seed layer 18A/18B is desired to provide a surface suitable for growth of the conventional hard bias structure 20A/20B. The conventional seed layer 18A/18B is typically composed of a layer of Cr, CrV, or CrTi.
The conventional magnetic hard bias structures 20A and 20B are used to magnetically bias the read sensor 16. For example, the conventional magnetic hard bias structures 20A and 20B may ensure that the free layer (not specifically shown in FIGS. 1 and 2) is stable and single domain. To ensure the stability of the read sensor 16, the conventional magnetic hard bias structures 20A and 20B should not be affected by external magnetic fields, for example from the recording media or write transducer. The conventional hard bias structures 20A and 20B are desired to have a high remanence magnetization, a large coercivity, and be thermally stable. The conventional hard bias structures 20A and 20B are thus typically formed of materials such as CoPt or CoCrPt.
Although the conventional magnetic transducer 10 functions, one of ordinary skill in the art will recognize that there are drawbacks. In particular, the magnetization of the conventional hard bias structures 20A and 20B may be disturbed during operation of the conventional magnetic read transducer 10. This is particularly possible when the conventional read transducer 10 is exposed to both a high magnetic field and a high temperature. As a result, the free layer (not separately shown in FIGS. 1 and 2) may be destabilized. Consequently, performance of the conventional magnetic transducer 10 may be adversely affected
Accordingly, what is needed is a system and method for providing an improved hard bias structure.